Hydrogen fluoride (HF) is a colorless fuming liquid or else a gas with a strong, irritating odor, which is extremely corrosive. Hydrofluoric acid is an aqueous solution of hydrogen fluoride. It is a strong acid which has highly caustic and corrosive effects on organic tissues, owing to the dissociated fluoride ions (F−).
Hydrofluoric acid is mainly used in industry as a raw material, in particular in the manufacture of stainless steel, of aluminum or of organic or inorganic chemical products, in oil refining, and in the manufacture of glass and of electronic components. Hydrofluoric acid is also present in various domestic products (for example antirust products). Consequently, the risk of exposure to hydrofluoric acid involves a large population of individuals.
Hydrofluoric acid can cause serious and painful bums on the skin and eyes. The symptoms, which are generally delayed and localized with dilute solutions of hydrofluoric acid, comprise erythema, edema and pain. As for the other acids, the seriousness of the bums depends on the concentration and on the temperature of the hydrofluoric acid and also on the exposure time. However, hydrofluoric acid differs from the other acids in that the fluoride ions rapidly penetrate the skin, thus being able to cause deep tissue destruction, soft tissue necrosis, tendinitis, tenosynovitis or bone decalcification. Contrary to other acids which can be rapidly neutralized, this process can continue for days if it is not treated.
There are several types of treatment for hydrofluoric acid burns, among which mention may be particularly made of the topical application of a magnesium oxide-ased paste[1] or else the injection of magnesium-based compounds such as magnesium sulfate or magnesium acetate[2].
Other treatments involve in particular the use of quaternary ammonium-based compounds[3] such as benzethonium chloride solution (Hyamine®)[3,4] or benzalkonium chloride (Zephiran®)[3,4]. However, treatment with Hyamine® requires saturating the burn area for a prolonged period.
Calcium gluconate-based infiltrations have for a long time been used to effectively treat hydrofluoric acid burns[1, 2, 4-7]. They make it possible to restrict the degree of edema or of necrosis caused by the hydrofluoric acid and prevent the fluoride ions from penetrating deeply. This laborious and invasive treatment is, however, generally reserved for cases of particularly serious burns, and is not suitable for giving first aid.
The gel based on calcium gluconate[8-12], in particular based on 2.5% of calcium gluconate, is moreover widely used in first aid for hydrofluoric acid burns. After rinsing with cold water, the gel is applied to the skin so as to prevent the injury from spreading. However, because of quite a limited demand, the calcium gluconate-based gel is not commercially available from the pharmaceutical laboratories. In France, this gel, which is also available in magistral preparation form, has the regulatory status of a hospital preparation. A ready-to-use gel based on carboxymethylcellulose/glycerol is thus manufactured and distributed by the Agence Générale des Produits de Santé [General Health Product Agency] (AGEPS, Paris, France). In the United States, this gel, which has not received approval from the Food and Drug Administration (FDA), is prepared extemporaneously by mixing calcium gluconate in solution or in powder form into a water-soluble lubricant. However, the absence of standardization of the preparation of the gel, and also the absence of stability and sterility tests, represent significant limiting factors for these noncommercial products. Moreover, these gel-type formulations do not allow wide distribution of the treatment. In addition, this distribution is generally carried out by hand or by means of a nonsterile spatula, which poses risks of microbial contamination.